What's the deal with probiotics? How this "good" bacteria can be beneficial for your health:

By now you've heard of probiotics. But what exactly are they, and why are they good for runners? The bacteria found in some foods—the live cultures in yogurt, for example—are probiotics, which help balance the microbes in the intestines. These friendly bacteria have long been credited with easing bloating, gas, and other uncomfortable issues. Now, mounting evidence suggests that probiotics confer additional health benefits, including fighting off colds, improving heart health—and ending emergency midrun pit stops. "As more researchers test the various strains, the scientific data backing probiotics grows," says Mary Ellen Sanders, Ph.D., a consultant who helps food companies develop accurate health claims about the good-for-you bacteria. Probiotics form naturally during some fermentation processes, and some companies have begun fortifying foods with the good bacteria, maki...